Expanding the diversity ofAccumulibacterwith a novel type and deciphering the transcriptional and morphological features among co-occurring strains

Abstract

Accumulibacteris the major polyphosphate-accumulating organism (PAO) in global wastewater treatment systems. Its phylogenetic and functional diversity has been continuously updated in recent years. In addition to its widely recognized two sublineages, Types I and II, here we discovered a novel type enriched in laboratory bioreactors. Core gene- and machine learning-based gene feature profiling supported that Type IIIAccumulibacterwas a potential PAO with the unique function of using dimethyl sulfoxide as electron acceptor. On the basis of the correlation between the similarity of ppk1 and genome, the number of ppk1-representedAccumulibacterspecies was estimated to be over one hundred, suggesting that the currently recognized species are only the tip of the iceberg. Meanwhile, multipleAccumulibacterstrains co-occurring in a bioreactor were investigated for their inter-strain transcriptional and morphological features. Metatranscriptomics of seven co-occurring strains indicated that the expression level and interphasic dynamics of PAO phenotype-related genes had minimal correlation with their phylogeny. In particular, expression of denitrifying and poly-P metabolism genes had higher inter-strain and interphasic divergence compared with glycogen and polyhydroxyalkanoates metabolic genes. A strategy of cloning rRNA genes from different strains based on similar genomic synteny was successfully applied to differentiate their morphology via fluorescence in situ hybridization. Our study further expanded the phylogenetic and functional diversity ofAccumulibacter. We also proposed that deciphering the function and capability of certainAccumulibactershould be environment- and population-specific.

Sequencing-guided re-estimation and promotion of cultivability for environmental bacteria

“…For soil samples, 500 g of soil was introduced into 2 liters of an inorganic salt solution (K 2 HPO 4 0.02 g L − 1 , MgSO4 •7H 2 O 0.02 g L − 1 , KNO 3 0.02 g L − 1 , pH is adjusted to 7.0) and then stirred using a magnetic stirrer for 2 h. For AS samples, sewage containing AS was allowed to settle for 1 h before collecting the supernatant. In the case of the sample from the EBPR bioreactor, an additional medium was prepared as the arti cial in uent 41 . These suspensions underwent sequential steps of clari cation, involving ltration through glass lter paper (average pore-size 2.7 µm glass lter papers, GF/D, Whatman, UK), 0.45 µm pore-size lter membranes, and 0.1 µm pore-size lter membranes (mixed cellulose esters, Merck, Germany).…”